Flatten a nested array of objects

flattenArrayOfObjects.js

const data = [
  {
    id: 251,
    name: 'Top level 1',
    parentId: null,
    children: [
      {
        id: 253,
        parentId: 251,
        name: 'Inner level 1-1',
        children: [
          {
            id: 456,
            parentId: 253,
            name: 'Inner level 1-1-1',
            children: []
          }          
        ]
      }
    ]
  },
  {
    id: 252,
    name: 'Top level 2',
    parentId: null,
    children: [
      {
        id: 254,
        parentId: 252,
        name: 'Inner level 2-1',
        children: []
      },
      {
        id: 255,
        parentId: 252,
        name: 'Inner level 2-2',
        children: []
      },
      {
        id: 256,
        parentId: 252,
        name: 'Inner level 2-3',
        children: []
      },
      {
        id: 257,
        parentId: 252,
        name: 'Inner level 2-4',
        children: [
          {
            id: 258,
            parentId: 257,
            name: 'Inner level 2-4-1',
            children: []
          }
        ]
      }
    ]
  }
];

function flattenArrayOfObjects(data) {
  const final = [];
  function walk(children) {
    if (!children.length) return;
    children.forEach(({ children, ...rest }) => {
      final.push({ ...rest });
      if (children.length) {
        return walk(children);
      }
    });
  }
  walk(data || []);
  return final;
}

const d = flattenArrayOfObjects(data);
console.log(JSON.stringify(d, null, 2));